A D2D communication method refers to that data packets are communicated by directly establishing a communication link between user equipments (UEs), such as a UE1 and a UE2, without needing via a core network, even without needing via a base station. FIG. 1 is a schematic diagram of D2D communications in the relevant art. As shown in FIG. 1, D2D communications may be performed between UE1 and UE2 under coverage of a base station (eNB1). However, if under coverage of a base station, control signaling of the UE1 and UE2 will be sent by the base station.
Before D2D direct communications can be established between UEs, a D2D discovery process, such as mutual discovery between the UE1 and the UE2, needs to be performed. For example, in order to achieve discovery of the UE1 by the UE2, the UE1 needs to transmit a D2D discovery signal, which may also be referred to as a beacon, in a time-frequency resource; and the UE2 may discover the D2D discovery signal transmitted by the UE1 by detecting the time-frequency resource. And quality of a channel from the UE1 to the UE2 may be known through signal detection.
It should be noted that the above description of the background is merely provided for clear and complete explanation of the present disclosure and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background of the present disclosure.